Beryllium-aluminum alloy



Patented Apr. 25, 1933 UNITED STATES PATENT OFFICE JOSEPH KENT SIITH, OFDETROIT, MICHIGAN, ASSIGNOB 'I'O DEVELOP- 11mm CORPORATION, OF NEWYOBK,N. Y., A CORPORATION OF DELAWARE BEBYLLIUI-ALUIDIUI ALLOY Io Drawial.

This invention relates to alloys characterized by extreme 1i htness andgreat strength, having metalhc beryllium as the predominating componentof the alloy.

Inasmuch as elementary beryllium in unalloyed form tends to greatbrittleness, and therefore cannot readily be rolled, forged, orsubjected to those other mechanical operations necessary to bring metalsinto readilyusable forms, especially those forms usedwhere extremelightness is required, it has been found necessary to alloy berylliumwith smaller uantities of aluminum so as to obtain an iiltra-lightmetallic material possessing those characteristics whichwill permit ofthe mechanical operations cited. The proportions of aluminum added tothe beryllium will vary in quantity with the requirements of thesituation the lower the quantity of aluminum adde the lighter theresulting alloy, but correspondingly greater are the difliculties ofmechanical manipulation.

When the aluminum content of the alloy is as little as ten percent ofthe total, great precautions are necessary in rolling or forging thealloy, while the alloy with thirty percent of aluminum, with a specificgravity of approximately 2.0, lends itself quite readily to all theusual methods of mechanical treatment. Alloys of about equal parts ofberyllium and aluminum are still easier to work, but they lack thegreater strength and superior lightness of the alloys lower in aluminum.The alloy approximating seventy percent baryllium and thirty percentaluminum represents best current practice in this series, presentin a'nice balance between the various factors involved.

However, the simple binary berylliumaluminum alloys, espite theirgreater strength as com ared with pure aluminum, leave much to lieresired inthe matter of strength, machinabiligv, resistance tocorrosion, etc. I have foun in myhinvention, that b adding,toan of thebery 'um-aluminum oy series in which beryllium predominates, smallquantities of manganese and zirconium, with or without simultaneousadditions of small quantities of molybdenum, significant increases instrength, machinability, resistganese,

Application Med December 28, 1931. Serial No. 582,657.

ance to corrosive influences, etc., can be effected, without anymaterial increase in the specific gravity of the alloy. Thevheavy metalsmentioned as addition agents-man- ZllCOIlllllD, never exceed fivepercent of the total weight of the alloy, and, in the preferredcompositions, these metals do not exceed two percent of the total.

If desired, such alloys can be made by the addition of the requisitequantities of the free heavymetals to a molten beryllium-aluminum alloy.The zirconium can also be added in the form of the carbon-freezirconium-alu mmum alloy which is so readily made by the reduction ofzirconium oxide with aluminum. Another method consists in melting thebe-. ryllium and aluminum together first, employlng as a flux a mixtureof the chlorides and fluorides of, calcium with some cryolite. To this.the zirconium (and, if desired, the molybdenum) is added in the form ofcompounds easily reducible in the circumstances, like zirconium, dioxideor. calcium zirconate (and calcium molybdate) Under the conditions,elementa zirconium (and molybdenum) is formed y reduction and entersinto the alloy. The manganese is added then by means of a cleansingalloy, comprising aluminum, magnesium and manganese. The magnesiumalmost all boils out readily, while the manganese and aluminumunite'with the primary alloy, resulting in the final multiconstituent'alloy..

As compared with the simple binary beryll1umaluminum alloy of seventypercent beryllium content, a similar alloy containing about one-halfpercent each of zirconium, molybdenum and manganese is more readilyworkable. flows better, casts better, has greaterstrength and resistanceto corrosion, and.

is more readily flexed without cracking. In sheet form, say from fifteento twenty thousandths of an inch in thickness, a stren of one hundred toone hundred and ten thousand pounds to the square inch is obtained. Insuch sheet form, the alloy is particularly useful for airplane wings andfuselage parts,

or wherever else the combination of ultramOlybdenum-should gthoslightness, strength and bendability without bre g is essential.

The presence of the heavy metals hardens the aluminum eutectic, givingthe multi-constituent alloy a relatively low coeflicient of friction.The alloy is, therefore useful for piston rings, pistons, and s' 1 armoving parts involving frictional effects.

In cast form, alloys covered by this invention have tensile stren hs.ranging from thirty thousand. to fifty ousand pounds per square inch.

While I prefer approximately 70% beryllium content, the invention isapplicable with approximately the following composition: beryllium fromabout to about aluminum from about 25% to about 40%, with the manganese,zirconium and molybdenum, if used, making up the balance inapproximately equal amounts.

A preferred analysis is Per cent Be 69.4 Al 29.0 Mn .6 Zr .3 Mo .5

99.8 Mg. added .7

The percentages are by weight. I claim 1. A beryllium-aluminum alloy ofapproximately the following composition: beryllium from about 55% toabout 70%, aluminum from about 25% to about 40% and manganese,molybdenum and zirconium in approximately equal amounts from about toabout 2 5% each.

2. beryllium-aluminum alloy of approximately the following composition:beryllium from about 55% to about 70%, aluminum from about 25% to about40%, and manganese, molybdenum and zirconium from about 11 to about 2each but not approximately in excess of 5% in the aggreate. g Intestimony whereof I have hereunto signed my name.

JOSEPH KENT SMITH.

